Air springs have been used as a component of a wide variety of motor vehicles and various other machines and equipment for many years. They are utilized to provide cushioning between movable parts and are primarily employed to absorb shock loads imparted thereon. A typical air spring consists of at least one flexible elastomeric reinforced sleeve extending between a pair of retainers, forming a pressurized chamber therein. The sleeve typically has a relatively inextensible bead core at each end for securing the sleeve to the retainers. Alternatively, the sleeve may be secured to the retainers by conventional crimping means. There may be one or more pistons associated with the air spring. The fluid in the pressurized chamber, generally air, absorbs most of the shock impressed upon or experienced by one of retainers. The retainers move towards and away from each other when the air spring is subjected to forces.
Both upper and lower retainers are conventionally formed of stamped metal. If the air spring has a piston, the piston, upon which the lower retainer is secured, may be metal or thermoplastic. A bumper, mounted on either retainer and provided for impact absorption and transference, is usually thermoplastic or thermoelastic, depending upon the forces which will ultimately be acting on the air spring and the forces to which the bumper will be subjected.
State of the art air springs utilize a steel bead plate which is rolled inwardly to securely affix a flexible member and ensure that there is an air tight seal between the steel bead plate and the flexible member. Because air springs are often used in corrosive environments, the steel bead plate is commonly coated with zinc, paint or some other coating to provide some degree of resistance to corrosion. During the rolling process to join the steel bead plate to the flexible member, the coating is often compromised or destroyed which leads to reduced effectiveness of the coating.
U.S. Pat. No. 4,784,376 discloses an improved air spring including: a pair of end members adapted to be mounted at spaced locations; a flexible sleeve formed of an elastomeric material containing reinforcing cords and having open ends sealingly engaged with the end members forming a pressurized fluid chamber therebetween; one of said end members having an end cap extending within one of the open ends of the sleeve and a clamp ring extending about said one sleeve end in clamped engagement with said end cap compressing the sleeve material therebetween; and an annular curved axially extending projection formed on a mating surface of the clamp ring extending into a concave recess formed in a mating surface of the end cap placing the sleeve in compression shear throughout radially spaced annular areas on opposite sides of said projection, and an intervening area within said recess between said annular compressive shear areas having a greater separation than the thickness of the sleeve material to permit the sleeve material to expand therein.
U.S. Pat. No. 6,926,264 discloses an air spring for absorbing and transmitting shock loads between parts moveable relative to one another, the air spring comprising a flexible cylindrical sleeve which is secured at each end to form a fluid chamber therein, a piston, the sleeve being secured at one end to a retainer and being secured at the opposing end by the piston, the air spring being characterized by: the retainer being integrally formed with an intermediate ribbed reinforcement structure to strengthen the retainer, allowing for direct mounting of the air spring to one of the moveable parts, the intermediate ribbed reinforcement structure of the retainer comprising an outer plate and an inner plate which are parallel to each other, and a plurality of ribs that extend between the outer plate and the inner plate.
U.S. Pat. No. 7,681,868 discloses an air spring comprising: a roll-off piston; a rolling-lobe flexible member made of rubber or elastomeric material; said rolling-lobe flexible member having a first opening lying opposite said roll-off piston and a second opening assigned to said roll-off piston; an attachment part configured as a head plate; said attachment part being made of thermoplastic or thermoset plastic and having air connection means formed integrally therewith; said attachment part having an outer rim and a conical region also formed integrally therewith; said outer rim and conical region facing toward said rolling-lobe flexible member; said attachment part defining a vulcanization region extending from the side of said rim facing toward said rolling-lobe flexible member into said conical region; and, said rolling-lobe flexible member being tightly vulcanized to said attachment part in said vulcanization region at said first opening while said rolling-lobe flexible member is seated in said vulcanization region.